Christopher Tidy wrote:

Anyway, I have a small problem with bearings. I intended to use
self-aligning ball races in pillow blocks, but it turns out that the
pillow block for a 1/2" diameter shaft is 5" long! So I can't get the
shafts closer than 5" apart unless I stagger the pillow blocks, which
will look messy. I want about 4" between the shafts, and I might make
this distance adjustable to allow different barrel sizes to be used on
the same machine.

Hmm. What if you mounted one pair of pillow blocks right side up and the other
ones upside down? Get 'em real close that way, but you'd have to modify your
design thinking a little.

Actually, you don't have to use pillow blocks. You can used flanged bearings
like this one: http://www.surpluscenter.com/item.asp?item=1-1489, but on the
sides of your tumbler, not on the floor. Again, a little different thinking.

Grant